There are two questions to ask when evaluating a political prediction, whether it's from Nate Silver, a pollster, an academic or your favorite Yahoo News predictions blog:

A) How useful was the prediction the day before the election?

B) How useful was the prediction the day after the election?

A great deal of attention is devoted to scoring the performance of various seers and prognosticators on Point A. The Signal went 50 for 51 in that regard, getting every state correct except Florida—of course it was Florida—in our last prediction before voters went to the polls. (We might humbly point out that our original prediction, announced in February, was precisely the same as the one we made on Nov. 5.)

Evaluating Point B is trickier. Have forecasters like Silver, who relies primarily on aggregating polls, taught us anything about how elections work and what motivates voters?

Last February, the Signal predicted that President Barack Obama would win reelection with 303 electoral votes to his opponent's 235--a prediction we made before the Republican party had chosen the identity of that challenger. This struck many people as absurd at the time: There were nine months of campaigning left, two conventions, several billion dollars worth of advertising, four debates, and untold bumps in the road for both sides.

As of Wednesday afternoon, 50 of 51 of those predictions are correct. We predicted the Republican would win Florida, where Obama presently leads by about 50,000 votes separating the candidates in Florida. If Gov. Mitt Romney can make up that distance, the Signal will have gone a perfect 51 for 51.

It's a sacred ritual of American elections that fans of the losing party threaten to leave the country, and then do not. We can see this phenomenon in effect by examining instances of the phrase "I'm moving to [country]" on Twitter around the time the election was called.

Curiously, Canada--long the imagined haven of liberals in years in which Republicans win--is the most popular choice. (Perhaps it's just close?) Australia comes in second, followed by ... Colorado? The people promising to move there are perhaps motivated by electoral news other than the winner of the presidency.

Update, Wednesday Nov. 7, 1:50 p.m.: Earlier today, Nevada was called for the Republicans and Montana for the Democrats, leaving only North Dakota unresolved. We give it a 90 percent chance of going Democratic.

This means we expect the Democrats to have 54 seats in the next Senate, plus the likely addition of independent Angus King of Maine.

Throughout the night, the Signal will be providing updates to our predictions for the presidency and Senate. This is not a real-time tally of results—Yahoo News has that covered—but rather a frequently updated set of our predictions, based on returns, exit polls and prediction markets.

Update, 11:22 p.m.: Obama is not longer virtually certain to win, just certain.

Update, 10:44 p.m.: Obama is virtually certain to win.

Update, 10:10 p.m.: The election continues to break as predicted. As we enter the last stage of the voting, we are waiting to see where FL, VA and OH end up.

Update, 9:50 p.m.: Ohio and Florida are now both strongly pointing toward an Obama victory.

As liftoff approaches Tuesday evening, the Signal will be focusing (like everyone else) on a small handful of states whose outcomes are not certain or nearly certain well before polls close. Here's a viewer's guide:

The no-drama states

There are 37 states, plus Washington, D.C., who we consider certain for one candidate or another. President Barack Obama controls 14 states and D.C., totaling 186 electoral votes. Gov. Mitt Romney controls 23 states, totaling 190 electoral votes. Virtually every news organization agrees on this list, with only minor variations. The only way Obama or Romney picks off one of these states is if the polls are wildly, wildly wrong and the entire country has shifted dramatically to one side.

As the last full day of the 2012 presidential campaign gets under way, the Signal's prediction remains the same as it was nearly nine months ago: President Barack Obama will win reelection with 303 electoral votes, winning Ohio and Virginia but losing Florida to Gov. Mitt Romney.

There is only about a 15 percent chance that we'll actually be correct, based on our prediction model, given the many combinations of close states that could go either way. Obama has a 24.8 percent likelihood of winning Florida, while Romney has a 40.8 percent chance of snagging Virginia and a 19.9 percent chance of securing Ohio. Romney needs to sweep all three states to secure the election.